QUANTITATIVE ANALYSIS OF THE IMPACT OF CRAFT LABOR AVAILABILITY ON CONSTRUCTION PROJECT PERFORMANCE

A shortage of skilled craft labor in the North American construction industry has been an unfortunate cyclic trend since the late 1980s. This shortage has been reported and discussed frequently by numerous past studies in the context of construction industry. The 2008 U.S. recession was at least one period when the craft shortage temporarily improved, as witnessed by spikes in construction unemployment rates above 20% due to the work slowdowns. However, the current economic recovery period is once again experiencing craft shortages in some sectors of the U.S. construction industry. Although the past literature provides wealth of information about influence of craft labor shortage on construction project, less attention has been given to quantifying the impact of craft labor availability on construction project performance. The primary contribution of this study to the body of knowledge is to fill the gap in existing literature by quantitatively modelling and elucidating the influence of craft labor availability on construction project performance as measured by safety, schedule, productivity and cost. Data from 97 construction projects completed in the U.S. and Canada between 2001 and 2014 were collected from two data sources. A number of t-tests and regression analyses were conducted in both databases to examine the significance of the influence of craft labor shortage on construction project performance. The primary analysis shows that projects that experienced craft shortages underwent significant higher growth in cost overrun, time overrun, safety incident and also lower productivity compared to projects that did not. Further analysis on two databases returned the following models: 1) a Poisson regression model that demonstrates a positive exponential relationship between increased craft worker recruiting difficulty and Occupational Safety and Health Administration (OSHA) Total Number of Recordable Incident Cases per 200,000 Actual Direct Work Hours (TRIR) on construction projects. 2) a statistically significant correlation between increased craft recruiting difficulty and lower project productivity and higher schedule overruns 3) a multiple regression models that demonstrate a relationship between increased construction cost overrun with two variables of increased actual cost and increased craft staffing difficulty. These models are intended to be used by project management team to perceive the risk that skilled craft labor variability poses on project safety, productivity, time, and cost performance. In addition, understanding the level of impact that craft shortages are having through robust statistical analyses is a first step in developing the motivation for industry leaders, communities, and construction stakeholders to address this challenge

Adjusted permutation method for multiple attribute decision making with meta-heuristic solution approaches

The permutation method of multiple attribute decision making has two significant deficiencies: high computational time and wrong priority output in some problem instances. In this paper, a novel permutation method called adjusted permutation method (APM) is proposed to compensate deficiencies of conventional permutation method. We propose Tabu search (TS) and particle swarm optimization (PSO) to find suitable solutions at a reasonable computational time for large problem instances. The proposed method is examined using some numerical examples to evaluate the performance of the proposed method. The preliminary results show that both approaches provide competent solutions in relatively reasonable amounts of time while TS performs better to solve APM

How Iranian cultural center’s public libraries use of information technologies for developing services

The goal of this study is describe how public libraries in Iranian cultural centers use of information technologies to developing its services. In this research paper, a structured questionnaire was used to collect data in 80 public libraries. Descriptive statistics method and Excel 2007 was used to analyzed data. In this study, libraries used of exit information technology in acceptable range but use of non-printed resources such as electronic and digital are weakness and only 12.5 percent of libraries contain this material. Librarian’s skills are suitable for used of IT in public and technical services but users need to necessary training for use of this facilities. The results of the present study show that information technologies facilities of all public libraries affiliated to the Art and Cultural Organization of Tehran Municipality are in desirable condition. Librarians and administrators also have full satisfaction of their libraries being equipped with new technologies. The interesting point in this context is to conform the nature and form of the provision of services in public libraries to the needs of users in different categories of sex, age and education

A Particle Packing Method for Pumpable Low-Shrinkage Flowing Concrete

In this paper, the applicability of the modified Andreasen and Andersen (A&A) particle packing model for designing pumpable flowing concretes, according to ACI 211.9R-18, is analyzed. An experimental investigation is undertaken to evaluate consistency, compressive strength, and shrinkage of flowing concretes designed with this model. The results show that the modified A&A model optimizes the particle size distribution of concrete ingredients and produces pumpable concretes according to ACI 211.9R-18. The distribution modulus of the model controls the combined grading, the ratio of coarse-to-fine aggregate, and the percentage of fine aggregate passing 300 and 150 μm. At a distribution modulus of 0.35, the model serves as the ACI’s recommended boundary limit for ideal-for-pumping combined grading. A high distribution modulus results in a high coarse-to-fine aggregate ratio and lowers the drying shrinkage of concrete. This insight enables a straightforward mixture design methodology that results in concrete that meets ACI 211.9R-18 recommendations